Reliability Provin KT-HA-804 Aftermarket Replacement Part for the Hitachi KT-HA-804 O-Ring Kit This kit will fit the following nailers: Hitachi N3804AB Includes: All the o-rings in the tool. Instructions with a schematic of the tool. O-Rings are color coded to aid installation. Manufacturer: Reliability Provin Part Number: KT-HA-804 This is a brand new tool part and comes with manufacturers warranty.